Self-Emulsifying Drug Delivery System (SEDDS) is a solid or liquid dosage form comprising an oil phase, a surfactant and a cosurfactant, characterized primarily in that said dosage form can form oil-in-water emulsion spontaneously in the gastrointestinal tract or at ambient temperature (referring generally to body temperature, namely 37° C.) with mild stirring. As the amount of the emulsifying agent increases, such a self-emulsifying system can form micro-emulsion in the gastrointestinal tract spontaneously, and thus is called Self-microemulsifying Drug Delivery System (SMEDDS). When SEDDS enters the gastrointestinal tract, it is firstly self-emulsified as emulsion droplets and rapidly dispersed throughout the gastrointestinal tract, and thus reducing the irritation caused by the direct contact of the drug with the mucous membrane of the gastrointestinal tract. In the gastrointestinal tract, the structure of the emulsion microparticulates will be changed or destroyed. The thus-formed microparticulates of micrometer or nanometer level can penetrate into the mucous membrane of the gastrointestinal tract, and the digested oil droplets enter the blood circulation, thereby significantly improving the bioavailability of the drug. The self-emulsifying drug delivery system is predominantly employed with respect to lipid-soluble and less water-soluble drugs. It can increase the stability and the bioavailability of the drugs.
Butylphthalide is a primary component in celeries and seeds thereof. It can be obtained by direct extraction from natural celery seed oil, or by synthesis. Chinese Patent for Invention No. 98125618.X disclosed the use of L-n-butylphthalide in the manufacture of an anti-thrombotic and anti-platelet agglutination drug, clearly demonstrating that L-n-butylphthalide can regulate the function of the NOS-NO-cGMP system and the metabolism of arachidonic acid in neuronal cells after cerebral ischemia. Chinese Patent for Invention No. 93117148.2 disclosed the use of butylphthalide in the manufacture of a medicament for preventing and treating a disorder caused by cerebral ischemia in a mammal or a human, wherein said butylphthalide is a liquid oil with no optical activity. It has an intense flavor of celery, and has the following formula:

Currently, butylphthalide is commercially available only in the form of soft capsule, that is, butylphthalide is dispersed in vegetable oil and then directly filled into soft capsules. Though such a dosage form can mask the unpleasant odor of the agent, yet its content is poorly dispersed in an aqueous phase, and the extent of its dissolution in vitro cannot be directly determined, which not only obstructs the quality control during the production of the product, but also affects the absorption rate of the drug to a great extent.
In addition, in Chinese Patent for Invention No. 02123000.5, the present inventors disclosed a technique to improve the water solubility of butylphthalide through the inclusion of cyclodextrin derivative. This technique not only masked the unpleasant odor but also increased the water solubility of butylphthalide. However, the amount of the primary component being used during the preparation of the inclusion substances is limited by the volume of the dosage form, and thus various dosage forms cannot be supplied to meet the requirements of patients. For example, the preparation of hard capsule dosage is limited by the loading capability, the preparation of tablets is limited by the suitability of tablet size, and the amount of the primary component in the inclusion substances cannot be too large. Furthermore, the inclusion process consumes more power, has more processing steps, is more complex to be operated, and requires more process control points (such as the temperature, grinding mode and strength, time, stirring rate and duration). So the industrialization of said product inclusion technique is relatively slow.